add scale_channels, swish, logistic(sigmoid), avgpool ; add enet_coco(EfficientNetB0-Yolov3).cfg

[thnkinbtfly]

Added Features

Add followings:

1. [scale_channels] layer with scale_wh=0
2. swish and logistic activation functions
3. [avgpool] layer, which is global average pool in darknet

Tested with enet_coco (I removed dropout layers from the original enet_coco.cfg)

Reproduce test with enet_coco

1. git clone the tkDNN forked darknet.

2. git apply following patch file to the forked darknet. Note that if you don't change the BN epsilon (different BN epsilon from the forked darknet #167), the final output will fail to be similar.

diff --git a/src/blas.c b/src/blas.c
index 7bfc752..8d3ddd8 100644
--- a/src/blas.c
+++ b/src/blas.c
@@ -289,7 +289,7 @@ void normalize_cpu(float *x, float *mean, float *variance, int batch, int filter
         for(f = 0; f < filters; ++f){
             for(i = 0; i < spatial; ++i){
                 int index = b*filters*spatial + f*spatial + i;
-                x[index] = (x[index] - mean[f])/(sqrt(variance[f] + .000001f));
+                x[index] = (x[index] - mean[f])/(sqrt(variance[f] + .00001f));
             }
         }
     }
diff --git a/src/darknet.c b/src/darknet.c
index f7d6a81..21b0f83 100644
--- a/src/darknet.c
+++ b/src/darknet.c
@@ -506,6 +506,9 @@ void run_export(char *cfgfile, char *weightfile, char *out)
         } else if(l.type == SHORTCUT) {
             printf("export SHORTCUT\n");
             // no weights
+        } else if(l.type == SCALE_CHANNELS) {
+            printf("export SCALE_CHANNELS\n");
+            // no weights
         } else if(l.type == ROUTE) {
             printf("export ROUTE\n");
             // no weights
@@ -515,6 +518,9 @@ void run_export(char *cfgfile, char *weightfile, char *out)
         } else if(l.type == MAXPOOL) {
             printf("export MAXPOOL\n");
             // no weights 
+        } else if(l.type == AVGPOOL) {
+            printf("export AVGPOOL\n");
+            // no weights
         } else if(l.type == REORG || l.type == REORG_OLD) {
             printf("export REORG\n");
             // no weights          

2. download enet-coco weights from official darknet repo

3. follow the steps to generate weights and input/outputs.
   Example :
   ./darknet export ../tkDNN/tests/darknet/cfg/enet-coco-wo-dropout.cfg enetb0-coco_final.weights layers

4. build tkDNN and

cd build
mkdir enet_coco_wo_dropout
cp -r ../../darknet/layers enet_coco_wo_dropout/ && cp -r ../../darknet/debug enet_coco_wo_dropout
./test_enet_coco_wo_dropout